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Many landslides were triggered by heavy rainfall from 29 June to 1 July 2017 in Ningxiang County, Hunan Province, China. A field investigation into one of the landslides, known as the Wangjiawan landslide, was undertaken on July 3, 2017, to understand the landslide mechanisms and the factors that triggered the event. The landslide is a translational and rotational slide that degraded downslope to an earth flow. It occurred on a steeply dipping mud-rich slate intercalation. Field investigation shows that the landslide had a movement rate of more than 25 m/s and had been triggered by up to 338 mm of continuous rainfall over 2 days. The landslide was fast-moving because it occurred on a steep slope and showed a rapid reduction in shear strength. The landslide resulted in nine fatalities and 19 injuries, most during initial rescue efforts. To mitigate a possible secondary landslide disaster, later emergency measures including evacuation of the survivors, setting up warning signs, and covering landslide cracks with plastic sheeting were adopted. [ABSTRACT FROM AUTHOR]

Subaerial landslides can generate impulse waves in reservoirs, fjords, and other water bodies and cause severe damage to the shipping industry, infrastructure, and human communities along the shorelines. Compared with deterministic hazard models, probabilistic hazard analysis is an important tool for assessing the intensity and exceedance probability of impulse waves generated by multiple landslide sources, which are essential for evidence-based risk mitigation and contingency planning. This paper proposes a methodological procedure for systematic probabilistic hazard analysis of impulse waves generated by subaerial landslides considering all relevant landslide sources and multiple uncertainties (i.e., landslide mechanisms, triggering scenarios, and material parameters). The main steps include: (1) definition of the source parameters by parameterizing the epistemic and aleatory uncertainties. In this respect, the logic tree, event tree, and Monte Carlo models were used to organize the uncertainties of landslide mechanism models, parametric scenarios, and material parameters, respectively; (2) estimation of generated waves based on a landslide dynamic analytical model and previously validated empirical wave models derived from prototype scaled experiments; and (3) aggregation of the hazard analysis results in the form of hazard maps and probability maps under parametric scenarios and a specific scenario. Considering the Wu Gorge in the Three Gorges Reservoir as a case study, soil slides and unstable rock slopes were analyzed to quantify the wave hazard along the reservoir under parametric and specific scenarios while considering rainfall and water level fluctuations. The results show considerable wave hazard in the Wu Gorge. For a 20-year return period, the maximum expected height of propagation waves is 14.41 m. The probability of experiencing propagation waves higher than 2 m in 20 years is over 50% in the river segment with high landslide density. The results of the probabilistic wave hazard analysis could be aggregated and disaggregated to accommodate specific requirements of wave risk management. • Hazard of subaerial landslide-induced waves was analyzed in a probabilistic manner. • Uncertainty was sourced from landslide mechanisms, scenarios and material parameters. • Hazard and probability maps under parametric scenarios assist risk management. • Probability maps under specific scenario were generated for contingency planning. [ABSTRACT FROM AUTHOR]